This paper reports a flexible and stretchable metamaterial-based “skin” or meta-skin with tunable frequency selective and cloaking effects in microwave frequency regime. The meta-skin is composed of an array of liquid metallic split ring resonators (SRRs) embedded in a stretchable elastomer. When stretched, the meta-skin performs as a tunable frequency selective surface with a wide resonance frequency tuning range. When wrapped around a curved dielectric material, the meta-skin functions as a flexible “cloaking” surface to significantly suppress scattering from the surface of the dielectric material along different directions. We studied frequency responses of multilayer meta-skins to stretching in a planar direction and to changing the spacing between neighboring layers in vertical direction. We also investigated scattering suppression effect of the meta-skin coated on a finite-length dielectric rod in free space. This meta-skin technology will benefit many electromagnetic applications, such as frequency tuning, shielding, and scattering suppression.

No abstract

No abstract

No abstract

Hydrophobic materials possess exceptional properties, making them extensively useful in daily production and life. However, developing low-cost and flexible hydrophobic materials remains a challenging task. In this study, a series of composite emulsions were prepared by introducing hydroxylterminated polydimethylsiloxane as a modifier into polyurethane acrylate via a solvent-free approach. The composite emulsions were then used to fabricate polymer films using the solvent evaporation technique. The effects of varying siloxane content on the properties of composite emulsions and polymer membranes were examined. The results showed that increasing the siloxane content improved the hydrophobic properties and flexibility of the film materials. Fourier transform infrared spectroscopy confirmed the introduction of the Si O Si group into the polyurethane chain structure, the absorption peak for asymmetric stretching vibration of Si O Si is at 1100 cm À1 . The mechanical properties test revealed that the film had excellent elongation at break (278.96 ± 0.01%), and a hydrophobic surface with a contact angle of 101.94 was obtained. The composite materials showed improved water resistance and thermal stability with the increase in siloxane content. The hydrophobic film is a promising material for application in decoration, architecture, and flexible wearable devices.